I am just curious what a fairly built 402 should max out at as far as RPM's. My problem is that I bought this car with the motor built and the previous owner does not have a lot of answers but here's what I do know.

1970 402 4 bolt, around 10.5:1 comp, fairly beefy cam, Edelbrock RPM manifold, Proform 750 DP, HEI ignition. This thing was built by a speed shop so I'm pretty sure it's balanced. Muncie m22 w/ 3.31 posi. It is a definite torque monster and pins you to the seat through gears but flattens out quikly at 6,200-6,300 rpm's. Between 3,000 & 6,000 rpm's this thing is screaming for a car w/3.31 gears.
Is there an easy answer?

Thanks- Frank

A safe RPM for a performance BB is usually around 6500. Some guys spin them much higher, and some don't take it that high. Basically, if the mill runs out at 6200, there isn't really a reason to spin it any higher.

I would venture a guess and say it would be fine at 6500, but there is no need to go that high if it falls off.

Chris

Red,

I was curious what most BBC fall of at. I keep hearing I should be able to push 7,000 out of a decently built motor. How about your 468?

Frank

Where a motor will fall off at depend on the cam specs and type. Some BB's will fall off at 5300, like my old 454, and some won't fall off until 6500. So, not knowing your specs it could be tough to tell.

7,000 is high IMO, especially in something you don't know exactly what kind of parts you have in your bottom end. Is it a 2 or 4 bolt main? Studs or bolts? Kind of crank? All things come into play. A hudralic cam will float at a lower RPM then a solid. Also, the heads play a major role. Oval or Rectangular ports. Ovals can fall off at high RPM, whereas Rectangles tend to flow better up high.

My 468 has a 4 bolt main with studs and a Solid roller cam. Guy I bought it from says it goes to 7,000 but as the power falls off just after 6,500 I try not to go over that. But, that is with a carb that I think to be too small, so it may be a little higher then that.

Personally, I would not take your motor up to 7,000. If the car noses over, there isn't really any reason other then saying "Yea, it goes to 7,000". The more RPM, the more of a chance of breaking things. Can you afford to rebuild your motor just because you wanted to see if it went up there? That would be a tough one to explain to the better half :)

But, its up to you. I am just giving you me $.02. You probably could get away with 7 grand, but I don't think you would be gaining anything.

Chris

Chris,

I appreciate your 2 cents worth. I will happy with my 6,200 rpms and will keep chasin' them Fords....

Frank

Chris,

I appreciate your 2 cents worth. I will happy with my 6,200 rpms and will keep chasin' them Fords....

Frank

:thumbsup: